Seam Type	Quality Tier & Application	Pros	Cons	Cost
Flatlock Seam (or Coverstitch)	Premium/Athleisure. Used for side seams and trims on high-quality knitwear, activewear, and heavy hoodies.	Flat finish eliminates friction against skin; extremely durable and highly elastic.	Requires specialized machinery	Higher
French Seam	Luxury/Tailored. Used for high-end shirts, blouses, and refined garments where a clean interior finish is paramount.	All raw edges are completely enclosed, resulting in a very clean, refined look.	Labor-intensive and time-consuming (two passes required); adds slight bulk; not suitable for heavy fabrics.	High
Twin-Needle Seam (or Chainstitch)	High Durability. Used for reinforcement on woven items like jeans (yokes, inseams) or for sturdy hems.	Exceptional strength and resistance to breakage; visibly signals durability.	Requires precise tension control; can pucker lightweight fabrics if not managed correctly.	Moderate
Overlock Seam (or Serged Seam)	Standard/Basic. Used universally for finishing raw edges on internal seams of virtually all garment types.	Highly efficient; prevents fraying and provides necessary stretch for knit fabrics.	Creates a slightly bulky seam allowance; is the minimum standard, not a sign of high quality by itself.	Low